1. Field of the Invention
This invention relates generally to double-acting bridge attachments for a guitar or other stringed instrument, and, even more particularly, to a cam activated tremolo bridge for a guitar or other stringed instrument.
2. State of the Art
“Floating” tremolo bridges are well known. The original patent to Fender in U.S. Pat. No. 2,741,146 includes a lever or a handle connected to a spring counterbalance or “floating” bridge pivotal on a knife-edged support. In such a mechanism, a pivot point is established, and the bridge pivots about that point. A counter spring is generally utilized to counteract the pull of the strings on the bridge. A lever or handle is provided for facilitating the pivoting of the bridge, while the user simultaneously plays the instrument. The guitar player manipulates the handle to modify string tension. For example, displacing the lever in a direction toward the guitar body causes string tension to decrease, resulting in a drop in the pitch. Conversely, displacing the lever in a direction away from the guitar body causes string tension to increase, resulting in an increase in the pitch. When the player releases the lever, the bridge returns to an equilibrium position due to the biasing effect of springs configured to counterbalance the tension of the guitar strings attached to the bridge. The neutral position is the position in which the guitar is tuned for normal play.
Because of the space required for the biasing levers and springs, floating type tremolo bridges are generally mounted to a guitar by routing or drilling the guitar body, or other similar operations. Unfortunately, this can be time-consuming and difficult, can cause undesirable changes to the body of the guitar and does not work well with hollow body guitars. Also, the mounting is typically permanent.
In addition, a tremolo that is based on a biasing system to return the bridge to the neutral state of equilibrium is extremely sensitive. String tension and biasing spring tension must be equilibrated to maintain pitch in the guitar. Therefore, if a string breaks, the overall string tension decreases, the equilibrium is upset, and the guitar goes out of pitch. Even placing a hand on floating type tremolo or damping strings while playing can upset the string/spring equilibrium. The guitar's tuning becomes out of order if the tremolo body is not completely restored to its neutral state of equilibrium after swinging the tremolo body.
In addition, the floating type tremolo bridge can make changing strings tedious and awkward and makes the initial tuning difficult. In general, tuning any one string creates a slight change in the tuning of the other strings. Thus, each string must be individually tuned and retuned multiple times in order to reach a satisfactory pitch relationship. Similarly, when a musician attempts to finger bend individual strings, the tune of the open notes is changed slightly, because any change in the tension of a single string moves the equilibrium point of the tremolo mechanism.
In the Rose U.S. Pat. Nos. 4,171,661 and 4,497,236, two improvements were established. In one improvement, the beveled ridge portion of the base plate was arranged so that it could be received and held in a tapered slot between the head of the screw and a flanged shoulder, thereby increasing the range of pitch change and improving the return to the initial tuned position and provided for lateral height adjustment of the tremolo. The other improvement involved functionally and physically integrating the bridge elements with the known art of combining fine tuners with anchoring means. In effecting the fine tuning, the bridge elements were provide with a constant radius, so that harmonic tuning would not be affected when establishing fine tuning. However fine tuning is limited to a range of about two musical pitches and is inadequate for bringing the strings to roper pitch for compensating string stretch, or achieving common alternate tuning commonly requiring a larger range of pitch change.
In the Shibuya U.S. Pat. No. 4,383,466, a pin was located in a hinge pivot to improve the return to the initial tuned position. This arrangement did not offer lateral height adjustment of the base plate and the field of rotation was not as great as in the Rose improvement.
U.S. Pat. No. 4,648,304 to Hoshino discloses a tremolo device wherein the strings are affixed to a series of reels that are rotated by means of a lever. The reels are not eccentric and depend on biasing action of a spring to maintain the reels in the neutral position. Hence, this device suffers from the defect inherent in all tremolos that rely on spring action to counter the biasing effect of the string tension.
It would thus be advantageous if a tremolo bridge on a guitar could be installed without drilling or routing the guitar, could be easily installed and removed, could maintain the pitch of the guitar when activated, and if strings are broken, could facilitate replacement of strings for the guitar.